1. Field of The Invention
The present invention relates to an image display apparatus of high resolution imaging which is provided with a pixel displacement unit which carries out optical displacement of the pixels of the imaging elements, such as those in a spatial optical modulator or a spatial light discharge unit, for each of two or more sub-fields of the image field. More specifically, the present invention relates to a projection image display apparatus of high resolution imaging which is applicable to a front or rear projector which projects a real image on the screen, and a head-mounted display or a view finder which projects a virtual image on the screen.
2. Description of The Related Art
Japanese Laid-Open Patent Application No. 04-113308 (Japanese Patent No. 293926), Japanese Laid-Open Patent Application No. 05-289044, Japanese Laid-Open Patent Application No. 09-152572, Japanese Laid-Open Patent Application No. 06-324320, and Japanese Laid-Open Patent Application No. 2000-98968 disclose a projection image display method which is made to carry out the optical displacement of the image of the spatial optical modulator (for example, the liquid crystal unit) optically for every sub-field, and projects the image at a resolution higher than the resolution of the spatial optical modulator.
The conventional image display devices of the above documents can obtain the twice (or 4 times) as many pixel, i.e., twice (or 4 times) as many resolution as the, as the respectively on the screen by carrying out displacement of the pixel optically by optical-axis shift to the two locations (or location of four every direction) perpendicular to the scanning line, and making the sub-field corresponding to the displacement into the two sheets or the four sheets.
Moreover, Japanese Laid-Open Patent Application No. 08-194207, Japanese Laid-Open Patent Application No. 09-230329, and Japanese Laid-Open Patent Application No. 09-015548 disclose an image display method which controls the amount of the optical displacement of the arrangement of the pixels and the optical-axis shift and the displacement direction thereof. The conventional image display devices of the above documents improve 3 times the resolution of the modulator by making the displacement of the three locations carry out in the same direction, and on the other hand, putting spatially, the RGB pixels which are produced by the spatial separation with the filters.
By performing the optical displacement, the delta arrangement of RGB is realized, or only some pixels indicated only in the specific portion are displaced, and the image display device which performs high-resolution imaging is also disclosed.
Japanese Laid-Open Patent Application No. 04-113308 discloses the spatial optical modulator in which the pixel size is smaller than the pixel pitch by one half. When the high-resolution imaging is performed by using the modulator and the optical-axis shift unit, the projection image-forming device of high resolution imaging which does not produce the lap between the adjoining pixels is also disclosed.
However, the pixel configuration is mainly determined in the aperture configuration of the spatial optical modulator, and since the permeability in the aperture is uniform, the optical intensity cross section which the contour configuration of the pixel in the field containing the pixel is usually the square, and is the beam profile (pixel profile) has the pixel profile which has the rectangle configuration which has the big step with the edge of the aperture.
For the reason, the gradation of edge of the image including one or more continuous pixels in the spatial optical modulator turns into a large spatial-frequency modulation, and the “resolution” measured by the optical intensity distribution of the line and space in the maximum spatial frequency of the pixel unit, and the “sharpness” by viewing become good. However, as the evaluation by viewing, the “hardness”, the “jaggies”, and the “image discontinuity” of the image become conspicuous. The problem corresponds to the disadvantage of the image of the liquid crystal over the image of CRT.
The pixel profile of CRT is the pixel profile that is similar to the Gaussian distribution form, and is a smooth image in which the “hardness”, the “jaggies”, and the “image discontinuity” are not conspicuous as the visibility. The “gradation discontinuity” stops simultaneously, being conspicuous as the results.
However, the “resolution” and the “sharpness” are not so good for the number of the pixels or on the basis of the number of the pixels.
On the other hand, the contour configuration of the pixel of the liquid crystal display which is the flat panel is the rectangle, and the pixel profile is the rectangle configuration.
For the reason, “resolution” and the “sharpness” are the images in which the “hardness”, the “jaggies”, and “image discontinuity” are conspicuous to being good on the basis of the number of the pixels, or the number of the pixels.
For the reason, even if it is monochrome character of binary data, the processing which performs the high gradation display which used gray scale about the “edge” portion, and stops being conspicuous in the “hardness”, the “jaggies”, and “image discontinuity” with the software processing to the font image may be made.
In the case of the conventional data projector of low resolution of SVGA or XGA class, the amounts of information of the one screen itself run short from the first for low resolution.
The number of the dots which forms the one character will be in the few state, in the case, it may become the impression which faded when the edge is not sharp, the distinction nature of the character may get worse, the visibility may tend to deteriorate, and the “hardness” as the visibility, the “jaggies”, “image discontinuity”, and “gradation discontinuity” may be conversely desirable.
However, in the low resolution about VGA, in the case of the projector of the object for the images of the case of the projector for the images, and the high resolution more than UXGA, and both for data, it sets.
It becomes important to consider the environment more by energy saving at the same time unlike the conventional projector for data of low resolution the request to the image quality is becoming enough as an amount of information of the one screen, realizes “the smoothness of the field and the edge” of the image by the high resolution on it, improves the visibility, improves the observer's recognition rate, reduces the rate of the error and reduces fatigue of the observer.
For the reason, the multiplication effectiveness according using the optical-axis shift unit to the one the twice of the original liquid crystal light valve, and further 3 times the number of the scanning lines of the, and the data linear density.
For example, consideration is given to performing the 4-fold high-resolution imaging or the 9-fold one for the number of the pixels. When the 4-fold high-resolution imaging is performed and pixel reduction is carried out to 50% or less of the conventional rates of the linear aperture (or the usual rate of the area-aperture is 25% of the 2's power), the pixel configuration of the projection image of projecting the reduced pixel with the projection lens is difficult to realize the “smoothness of the field and the edge” which is demanded in the case of the high resolution, unlike the case of the conventional projector of low resolution.
It is the projection lens, when the conventional pixel of the spatial optical modulator whose optical intensity the contour configuration is the square configuration and is the rectangle configuration is projected and projector equipment is produced.
Although the beam profile of the rectangle configuration is changed and it becomes the pixel on the screen according to the MTF frequency characteristic of the projection lens at the same time the square pixel is expanded on the screen for the predetermined magnification, it is changed so that it may have curvature with the usually big edge of the ends of the rectangle configuration.
Although the resolution of the projection lens for data projections differs greatly also with the kind of the image information, and the product price strap, in order to usually harness the resolution of the liquid crystal light valve in high cost effectively relatively, 30% or more is required for MTF in the highest spatial frequency which the pitch of the pixel gives, and it is 50% or more preferably.
If the projection lens is MTF 100% in all spatial frequencies at the time, since the image in the liquid crystal light valve and the expansion image on the screen have the relation of 1:1 completely, the pixel profile is the rectangle configuration and the “hardness” as the visibility, the “jaggies”, and “image discontinuity” are the very conspicuous images like the LCD monitor as a usual flat display.
Actually, since MTF of the projection lens is not completely 100% in the entire spatial frequencies, corresponding to approaching the sine-wave-pixel profile simply, image quality can receive the deformation, and the beam profile of the rectangle configuration of the pixel can reduce the “hardness”, the “jaggies”, the “image discontinuity”, etc.
However, even if it projects the reduced pixel of 50% or less of the conventional rates of the linear aperture with the projection lens of comparatively low MTF and forms the projection image, the rate of the aperture is small, and there is the space between the adjoining pixels when MTF of the projection lens is dropped to the state where the “hardness”, the “jaggies”, the “image discontinuity”, etc. are not conspicuous. The resolution of the image also deteriorates simultaneously, and the “sharpness” of the image is reduced.
When MTF of the projection lens becomes still smaller than 30%, the inclination becomes still larger, improvement in the image quality when performing high-resolution imaging by carrying out the optical-axis shift in the case is almost lost, and it becomes impossible to display only the deteriorated image instead.
This is the case when the focus location of the projection lens is shifted and the focal location is removed. As the pixel profile which has performed pixel reduction simply by making the rate of the aperture into 50% or less of rates of the linear aperture, the pixel profile which decreases the “hardness”, the “jaggies”, “image discontinuity”, etc. is unsuitable in the case of high-resolution imaging.
Japanese Laid-Open Patent Application No. 09-054554 discloses that, when carrying out the optical-axis shift and performing high-resolution imaging, the above-mentioned method of focusing with the focusing lens smaller than the comparatively large aperture of the penetrated type liquid crystal panel
FIG. 16, FIG. 17A, and FIG. 17B show an example of the conventional image display apparatus which combines the penetrated type micro lens to the penetrated type liquid crystal panel as the means for changing the pixel size, which is disclosed in Japanese Laid-Open Patent Application No. 09-054554.
FIG. 16 shows the example of the micro lens which has the penetrated type liquid crystal light-valve with the specific aperture, and the circular contour which reduces pixel size rather than the small aperture which is restrained and produced by the active unit.
FIG. 17A and FIG. 17B show the state of the continuation pixel profile which is formed when the optical-axis shift of the pixel profile of the rectangle configuration having the pixel reduced by the composition of FIG. 16 is carried out.
In FIG. 16, reference numeral 101 is the incident-light ray, 102 is the focusing optical system, 102a is the minute lens, 103 is the indicating element, 103a is the opening of the pixel which is provided in the indicating element 103, 101a is the picture element which is formed with the focused light ray, and 104 is the outgoing ray.
The incoming ray 101 which is incident to the opening 103a of the pixel of the indicating element 103 is focused by the minute lens 102 in the focusing optical system 102, and the focusing pixel 101a is incident to the opening 103a and passes through it.
The ray which comes out from the opening 103a after this penetration turns into the outgoing beam 104.
FIG. 17A shows the state of the continuation pixel profile formed when the optical-axis shift is performed without reducing the pixel size.
FIG. 17B shows the state of the continuation pixel profile formed when the optical-axis shift is performed when reducing the conventional pixel shown in FIG. 16.
Both the states of FIG. 17A and FIG. 17B are shown to explain the operation of the projection expansion apparatus using the penetrated type liquid crystal light valve and the optical-axis shift unit when performing the high-resolution imaging that is the 2-fold one in one direction.
As shown in FIG. 17A, when not carrying out pixel reduction, the pixel is slightly reduced by the aperture with the less than 100% area opening factor determined by the arrangement of the active unit (not shown) prepared in the pixel.
Even if the pixel profile in the case is the rectangle configuration limited by the aperture and uniform lighting high-resolution it by optical-axis shift using such a pixel profile. While the resolution is not improved in spite of the optical intensity of these overlapping portions having increased in step and having used the optical-axis shift when the pixel profiles of the shifted rectangle configuration overlapped, there is the problem that the “discontinuity” of the image will be conspicuous.
When pixel reduction is carried out, the width of face of the pixel profile of the rectangle configuration is made into 50% or less of the pixel pitch, and the lap between the adjoining pixel profiles is lost, but the resolution is improved as shown in FIG. 17B.
However, similar to the case of Japanese Laid-Open Patent Application No. 04-113308, the pixel profile shown in FIG. 17B is the pixel profile of the rectangle configuration in which the rate of the linear aperture is 50% or less. The “sharpness” as the visibility and the “resolution” are good, but the “hardness”, the “jaggies”, and the “image discontinuity” are conspicuous like the LCD monitor as a usual flat display.
Although the can be reduced by changing the MTF characteristics of the projection lens, the “resolution” and the “sharpness” will deteriorate conversely.
For the reason, as the image projector of high resolution which realizes high-resolution imaging, or a data projector of high resolution, the projection image which secures the “sharpness” which is demanded, unlike the case of the conventional projector of low resolution, taking advantage of the high resolution imaging by increase of the number of the pixels in the case of the high resolution imaging, and the “smoothness of the field and the edge” cannot be realized by shifting the pixel profile using the optical-axis shift unit.
Such a problem cannot be resolved if the pixel profile of the projection image having the pixel size reduced is in the rectangle configuration even when the contour configuration of the pixel is changed to the circular configuration with the focusing optical system as shown in FIG. 16. It is difficult to achieve the purpose of high-resolution by increase of the number of the pixels using the optical-axis shift unit.
Furthermore, in the case of Japanese Laid-Open Patent Application No. 04-113308, the pixel size is reduced, but it is materialized only on the assumption that the beam profile of the rectangle configuration for which pixel reduction of 50% or less of rates of the linear aperture is needed in order for the pixel profile not to lap, and the description about the pixel profiles other than the rectangle configuration is not accepted at all, but is produced by the pixel profile of the rectangle configuration.
On the other hand, in the case of Japanese Laid-Open Patent Application No. 09-054554, it is indicated that the brightness level, i.e., the optical intensity, is improved and the contrast is improved, since the average luminance per 1-pixel area does not improve even if peak luminance improves, except that the rate of the effective aperture of the pixel by reducing the pixel improves, there cannot be no improvement in optical use efficiency.
Generally, the luminance of the case is reduced by the same or loss by the added optic on the basis of the area of the original pixel.
Furthermore, the case of Japanese Laid-Open Patent Application No. 09-054554 is premised on the rectangle configuration as a pixel profile of the reduced pixel, as shown in FIG. 17B.
For the reason, when improving and doubling the resolution in one direction using the optical-axis shift unit, in order for the pixel by which the optical-axis shift is carried out not to lap like FIG. 17A, it is necessary that the pixel reduction is at least 50% or less of the rate of the linear aperture.
For the reason, the F value of the reflection light ray is increased almost two times the F value of the incident light determined by the lighting optical system, and a very bright lens as the projection lens is required.
On the contrary, if the projection lens of the optimal F value is used when not carrying out pixel reduction, the reflection of the projection lens will arise and it will become 25-50% of very low optical use efficiency as compared with the case where pixel reduction is not carried out.
Moreover, the case where the F value of the reflection light becomes brighter than 2 double part by many yields of the optical system used for pixel reduction arises.
Under the influence, the F value (it is the ½ twice as many projection lens as the at the F value) of the brightness of 2 twice is used at the angle of the outgoing beam, but the optical use efficiency will decrease. For the reason, when carrying out pixel reduction, the improvement in optical use efficiency is a very important problem. However, there is no teaching in Japanese Laid-Open Patent Application No. 09-054554 as to how to solve the above-mentioned problem.